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Progressive Freezing Method for Concentrating Tetrahydrofuran (THF) Remained in Grignard Reagent Wastewater

Abstract:

Progressive freezing technology was developed as a promising method to concentrate tetrahydrofuran (THF) remained in Grignard reagent wastewater. Effects of freezing temperature, ice formation rate, and seeding ice on ice purity were characterized. Results indicated the peak removal efficiency of chemical oxygen demand (COD) with the concentration of 3,050 mg⋅L−1 occurred at the lowest ice formation rate of 20% and −4.0°C. The minimal ice electrical conductivity happened at −6.0°C with the ice formation rate of 40%. Seeding ice improved ice purity in the range of −0.5 to −1.0°C. Subsequent test ran in plant revealed the potential application of this approach to concentrate THF from Grignard reagent wastewater. COD removal efficiency peaked at 98.09% at the stirring rate of 200 rpm and the cooling gear of 1 block. Moreover, the theoretical energy consumption was 38.26 kW⋅h per one ton of wastewater.